Update README.md

improve screenshot layout

Author: lischilpp

README.md

@@ -7,11 +7,6 @@ You can enter any arbitrary numbers for the four matrix values, and the resultin
  [Interactive Page](https://lischilpp.github.io/Linear-Transformation-Plotter)
 
 # Screenshots
-## Identity
-<img src="screenshots/identity.png" width="300" alt="Identity transformation">
-
-## Skew Y
-<img src="screenshots/skew_y.png" width="300" alt="Skew-Y transformation">
-
-## Mirror X
-<img src="screenshots/mirror_x.png" width="300" alt="Mirror-X transformation">
+Identity |  Skew Y | Mirror X
+:-------------------------:|:-------------------------:|:-------------------------:
+![Identity transformation](screenshots/identity.png)  |  ![Skew-Y transformation](screenshots/skew_y.png) | ![Mirror-X transformation](screenshots/mirror_x.png)